Bruno Loff:
Also, cleaning the energy body is the sole purpose of doing yoga asanas.
Asana (as right posture) has three benefits: your body becomes steady, pleasent and relaxed. It's a great achievement and condition for concentration. You could see nervousness manifesting as permanent little movements and tension or pain in the body as blockages or impurities, yeah, and you have to deal with them to achieve asana. But they are bodily symtoms, and the cause can be emotional or mental. Honestly, if you are a beginner who does not percieve anything pranic or energetic, I'd view this process as psychological work and purification. When you percieve prana well, it'll be a reflection of your whole psyche, your body, emotions and mind, and help you integrate it.
When you're strong enough that new stuff and stories from your life don't upset you too much anymore and sorted out a little so that you don't have major issues with yourself and your past, you're already quite a bit "pure". The more you can remain steady, at ease and relaxed (it's not only physical), the more you've achieved asana in the yogic sense, the "purer" you / your energy body have become.
Through asana practice (movements) you can become strong enought to remain in your meditative asana (that means you remain steady, at ease and relaxed) for a long time (two-four hours). Haven't done this, guess you'd need at least an hour of daily asana practice for this.
I've done the spinal breathing for five weeks, only once daily, 10 minutes. The root of the spine gained quite a bit of plasticity (and bubbliness) and there comes some excitement from the perineum, it's easier to trace the spine, and ajna has become even more penetrant. No unbearable bliss, if you want it, maybe twice a day would really be worth it. I stopped it last week.
I'll keep Yogani's advice to do something before each sit, but return to the microcosmic orbit, 15 minutes a day. So far, the last three days, it seems as if it (like a full-body circuit à la NEW) has benefitted from the spinal breathing (or maybe my perception has gained sharpness, it's hard to tell), but the MO is definitely more chilled out. And it's a lot better to detect disturbances and connections between emotions and thoughts and energetic contractions / tensions. Only sensed these tensions in the perineum so far, but the last few days were promising. I'll keep you posted when I finished 5 weeks with this practice.
Edit: If you ask me, we could start a new thread about purification and for contrasting different practices. Definitely interesting topic, and we don't have much data yet. By far the most spectacular results I got from kundalini yoga, a nut-sized chakra (wheel) in my lower abdomen, as stronlgy felt as if you have a fast spinning gyroscope in your hand. But I cannot write about it in general as I only did one single practice (with different static asanas, partly with hyperventilation, 20-25minutes) for six weeks.